***Cont../ Useful Information for Electricians & Apprentices***

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O.S.G.. The use of other methods’ of determining Maximum Demand is Not Precludedwhere Specified by the Installation Designer

FirstlyI make no Apologies for the Way am Writing on any Matters . it can be a first day Apprentice or some one Needing aJog of Memory .
Sowe are all in the Same Boat . “ To Learn “

For the Apprentices . The Day we stop learning is the Day we hang Upour Tool-Bag

CookerDesign Current Calculations

Thefirst thing you have to do is get Your Head around the Calculations !!

(From a Design point of View ) 2392-10

DomesticInstallation Oven(s) & Hob(s) are to be Calculated upon their MAXIMUM LOADING
Startwith a simple Calculation ( An Oven has a rating of 2kW ) 2000

(I = P/V ) Formula … I = 2000 ÷ 230V = 8.70A …. Weare Using the Unit Amps


2392-10/ Domestic Installation Oven(s)

Ovenhas 4 Rings ( 2 x 1kW ) & ( 2 x 1.5kW ) & Grill ( 2kW ) & Oven (3kW )

-Controlled via a CookerSwitch with a Socket outlet .

Asa Designer . we’ll have to Apply Diversity ??

Important )- Diversity allowance to be Applied to the FULL LOAD CURRENT for CookingAppliances .

TheO.S.G. is telling us . Purpose of the Final Circuit fed from theConductors )
O.S.G.Table 1B p/97 – column (3) Cooking Appliances → At the Top of the Page Note : Type ofPremises ( 2392-10 → Household Installations ) Domestic Installation(s)

DomesticInstallation(s) Only O.S.G. - 10A + 30% f.l – Full Load ) of connected Cooking Appliances in the Excess of 10A+ 5A if a socket-outlet is incorporated in the Control Unit . ( C.C.U. ) – 45A + 13A Socket Switched with Neon .

Fromyour point of View ( The First 10A ofthe rated current plus 30% of the reminder ( Plus) 5A if the Control Unit incorporates s Socket.

Calculations)- You bank “ Hold OFF“ the first 10 Amps of the Maximum Load Current )
The10A will be used at the End of the Calculations’

-So your Work out the Total Power Rating & then calculate the Full Load Current

Calculations)- Power = ( 2 x 1 ) + ( 2 x 1.5 ) + ( 2+ 3 ) = 10kW

I= 10000 ÷ 230V = 43.48A … round it up to the first four numbers43.47826087 ( 48 ) 43.48A

UsingDiversity allowance stated ↑↑ ( 43.48A sub 10A = 33.48A )

I= 33.48 x 30 ÷ 100 = 10.04A

Youradding the ( 5A ) for Socket outlet . I = 10A + 10.04 + 5A = 25.04A )- Asa Designer this is your Expected Current Demand .

Remember )- Supply Cables Rated to suit DesignCurrent ( Iz )

 

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2392-10 : Division of Installation .

If we look atRegulation 314.1. :coolgleamA:

The Choice is Your as Designer(s) .

314.1 . does not mention . Thata Ring Final Circuit should be the Automatic Choice for Socket – outlets

• Ring Final Circuit .
• Radials

 

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Apprentices

Important to remember that where a Residual Current Device does not ( Incorporate OvercurrentProtection ) A Circuit Breakermust be Used . :gettree:

 

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Something I knocked up . ( PIR ) one day ??

Regulations . 612.2.1. ( R2 ) Continuity of ProtectiveConductor(s) . :banghead:

Apprentices .

There’s to much writtenabout Ring Final Circuits . Method 1

Method 2 (- usesthe Wander Lead or ( R2 ) Method

Mainly used on MainProtective Bonding Conductor .

Reason : You must Confirm the Continuity of Main Protective Bonding Conductor . ( A ◄► B )

Firstly : Permission beforehand as this may have SafetyImplications . “ IMPORTANT “

i) Safe Isolation . before you begin .
ii) Disconnect any Parallel Paths . This can be done byDisconnecting ◄► MainProtective Bonding Conductor . from the ( MET)
iii) Disconnecting ◄► MainProtective Bonding Conductor . from BS-951/ Earth Clamp .

-&-s . Null the leads . Why ?? . Wander Lead will add aconsiderable résistance to your Instrument .
-&-s . Instrument does NOT have a Null function . Subtract the résistancefrom the Actual Reading .

-&-s . Readingcan be recorded as the Résistance of the ( CPC / R2 ) on the Schedule of Test Results . Example .Regulation . p/341 . Continuity ( R2 * / Ω ) Dead Test

Remember (- -&-s . to Reconnect Parallel Paths . )

-&-s . Earthing Clamps must conform to BS-951 / “Safety Electrical Connection – Do Not Remove “ Etc

Remember . Anything to do with Earthing . -&-s are allover you like a Bad Rash . Yeah :gettree:

 

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Apprentices : amUsing the Wording to help you Understand someConcepts of Earthing . Regulation .P/32 . fig2.1 :26:

From the ( Service Cut-out ) 16.0mm[SUP]2 [/SUP] → Earthing Conductor to the → ( MET ) → 10.0mm[SUP]2 [/SUP] → Gas / Water (- MainProtective Bonding Conductor .

Safety EarthConnection . Do Not Remove .

TT System (- EarthingConductor from the ( MET ) → Earth Electrode .
TT System ( MET ) → 10.0mm[SUP]2 [/SUP] → Gas / Water (- MainProtective Bonding Conductor .

541.13. Warning Notices : Earthing & BondingConnections

SafetyElectrical Connection . Do Not Remove .

 

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Final Circuit for Lighting . Loop-in method is Usedfor wiring a ( Final-Circuit ) for Lighting . :thinking:

 

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The Magnetic Mechanism usesa solenoid with an Iron piece . Etc .Used for ( Short-Circuit Currents / Fault Protection )

• Thermal Mechanism .
This mechanism uses a ( Heat Sensitive Bimetal Element) it is Used for ( Overload Circuit Protection )

Advantages . Immediate indication of ( Fault Current) by Identifying which circuit the ( Fault )occurred on
Advantages . Reclosing can be Effected at Once after the ( Faulthas been Cleared )

 

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Apprentices : Learning Curve . Point to Note :

RCDs . Because the RCD trips in milliseconds ( mS ) 30 / milliamps. ( mA )

Regulation . Definitions – p/29 ( RCCB ) :speechless:

• The Short Circuit doesNOT Produce an Imbalance between the Line & Neutralcurrents in the ( RCCB ) They are still out there on the 16[SUP]th[/SUP]Edition .
• The ( RCCB ) does Not Incorporate an OverloadFunction .

UsefulJunk :

MCB – The difference being it has Three-States in can be . ( OFF) → ( ON ) → ( Tripped )
CircuitBreaker : is designed with a ( Switch ) in orderto Turn a Circuit – ON / OFF .

(can be used for Isolation / FunctionalSwitching ) Table 53.2.

 

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Miniature Circuit Breaker . ( MCB) :earmuffs:

AdvantagesCan operated by Hand or Automatically .

• The Automatic Operationis done by Using . Magnetic or Thermalmechanism

 

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Thisis a Sub-Board . ( Main Board is Isolated / LockedOFF ) :speechless:

ThisTest in done on the 16[SUP]TH[/SUP] Edition ( No- RCDs ) … Just Main Switch 100A . Example

Insulation Résistance Test (IR )

Example(- 6 / Way

ThirdTest:

Dead Test /Safe Isolation procedures should be carried out . Priorto Testing

Thiscan be carried out at the Main Switch ( 100A ) at the Distribution Board . being Tested

Youmust Insure that the ( Switch ) in the ( On-position ) with allthe ( Circuit breaker(s) for all circuits to be Tested .

indoing this . ( You must Insure that – all Lamps / Dimmer switches or Appliancesare RemovedPrior toTest

theTest is carried out between the ( Line & Neutral ) Usingan Insulation Résistance Tester / set on( 500V / MΩ. Scale )

•500V Scaleis Applied / A reading should be Greater that (≥ 999 . is Obtained )
TheTest is then carried out On .

theTest is carried out between the ( Line & Earth ) Using an InsulationRésistance Tester / set on ( 500V / MΩ . Scale )
•500V Scaleis Applied / A reading should be Greater that (≥ 999 . is Obtained )

TheTest is then carried out On .

theTest is carried out between the ( Neutral &Earth ) Using an InsulationRésistance Tester / set on ( 500V / MΩ . Scale )
•500V Scaleis Applied / A reading should be Greater that (≥ 999 . is Obtained )

Thisproves that the ( Line & Neutral ) arenot Touching .
Thisproves that the ( Neutral & Earth )arenot Touching .
Thisproves that the ( Line & Earth ) are not Touching .

(No Breakdown of the a ConductorInsulation ) -&-s

MCBs/ Red or Green indicator provides Immediate Visual Indication of Devices
ForIsolation Functions (- Green / OFF . Red / ON .

 

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Inspection& Testing , before an Installation is Fully Commissioned is a Critical Task. :53:

“ Visual &Testing “
:juggle2:
Apprentices & 2392-10 . Ring Final Circuit .

This is just the same as if you where doing it onConsumer Unit ( DEADTEST )

On Industrial Premises’ .

When doing Insulation Resistance Testing on a Ring Final Circuit it have to “ Be “ Individually . ( IR ) as it is NOT Possible to carry out InsulationResistance on Industrial Installation as a Hole ’ . Yeah

Firstly . Ring Final Continuity Checks .

This is done by disconnection of Both Ends of the Line ( Neutral &Circuit Protective Conductor ) from the Board.

Continuitycan be Checked for Each Conductor .

Check : Null out yourLeads / Megger 1552 .

Step - 1. Line to Line . 0.26Ω . ( Lower )
Step - 2 . Neutralto Neutral . 0.26Ω . ( Lower )

Step – 3 . CPC to CPC . is aReduced Cross-Sectional Area its Résistance . ( Which then is “ Higher “than the Phases0.33Ω .) being/ Line / Neutral

Next Step .
( DB ) “ Distribution Board “Cross/ Connect . Neutral to Line. Vice. Versa
( DB ) “ Distribution Board “Cross/ Connect . Line toNeutral

The Résistance of the ( Line& Neutral Résistance at any SocketOutlet ) Readingshould be the Same . ? 0.15Ω

• IndustrialInstallation / Wired in Single(s) Core Cables “ Same Size “ ???
• If Readings ( Increase ) from point of supply . You may have ( Mixed ) up the Line& Neutral Conductors . off the Two Legs of the Ring .

Double Check (- The Readings should be ??

Line :0.26Ω
Neutral: 0.26Ω + ( 0.26Ω + 0.26Ω = Combined 0.52Ω )

¼ Combined : 0.13Ω

“ Spurs “ will give a SlightlyHigher Reading(s) it will give the Résistance of the Spur Conductors’ .

Next Step . ( Final )
( DB ) “ Distribution Board “Cross/ Connect . Lineto CPC . Vice. Versa … Readings / ( R1 + R2 )
( DB ) “ Distribution Board “Cross/ Connect . CPCto Line .

The Résistance of the ( Line& CPC Résistance at any Socket Outlet ) Readings / ( R1 + R2 ) Polarity checked at this Stage . as well as Visual Inspection on Terminals .

The reading should be the Same ( ¼ Combined Résistance : ofthat of the Line &CPC .
Spurunits will be Slightly Higher .

The Highest Reading Obtained . will be Recorded . ( R1 + R2 ) Schedule of TestResults. ( Line / 0.22Ω + Neutral / 0.23Ω) R2 – CPC /0.3 . ( R1 + R2 ) 0.52Ω

Whilst the Ring Conductors are Disconnected it make sensethe do Insulation Résistance Test . at this Point .

 

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2392-10 / Some Regulation for Installing a ConsumerUnit : The WHY.S :speechless:

416.2. - Note : Barriers or Enclosures are Intended to prevent ( Contact with Live Parts )

(- Cable Entry Sealed to ( IP4X ) 416.2.2.Horizontal Top Surface of a Barriers or Enclosures .

(- Enclosures Sealed to ( IP2X i.e. BLANKS FITTED )

ii) After disconnection of the Supply to ( Live Parts ) againstwhich the Barriers or Enclosures afford ( Protection ) Restoration of theSupply being possible ( ONLY ) after
replacement orReclosure of the ( BARRIER or ENCLOSURES ) Etc .

(- Sufficient Space to allow Cables to Bend into Devices .
MechanicalStresses . 522.8.3.
The ( Radius ) of every ( Bend ) in a wiring systemshall be such that conductors or Cables do not suffer ( Damage & Terminals are NOT Stressed )

Plain English(- Such that Conductors’ & Cables shall NOTsuffer Damage )
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This is Whatyour Assessor is Looking for . - (- Cables Sheaths NOT stripped Outside ofEnclosures . 526.9.

Cores of ( Sheathed Cables ) from whichthe Sheath has been Removed & Non-sheathed cables at the termination ofConduit . Ducting or Trunking shall be Enclosed as required by Regulation .526.5.

(- EnclosureMaterialAppropriate to the Environment . 522.6.1.
Wiring Systemsshall be selected & Erected so as to Minimize Mechanical Damage . e.g. .damage due to Impact . Abrasion . Penetration . Compression or Tension . DuringInstallation .

( T ) (- Diagrams “ must be Provided .514.9. / 514.12.1.
A legibleDiagram . Chart or Table or equivalent form of information shall be providedindicating in particular . ( Circuit Detail Labels )

(- Unit Adequately Fixed . 416.2.3.
A Barrier orEnclosure shall be Firmly Secured in Place . ETC

Division ofInstallation . 314.1.
InstallationCircuit Arrangement . 314.4.
Protected byAppropriate Devices . MCBs – 433.1.1. / Protection by One Device ( iii )

514.8.1.Identification of a Protective Device : MCB .
A ProtectiveDevice shall be arranged & Indentified so that the Circuit Protected may beeasily Recognised .

511.1 ) Complieswith the relevant requirement of the applicable British Standard / Harmonised Standard .
510.2. ) ManufacturesInstructions are followed .

TheProtective Devices in the Consumer Unit are adequate for the Prospective FaultLevel . Conditional rating . ??
313.1/ 512.1.2. ( ii )

TheRating of the MainSwitch or Circuit Breaker is sufficient for the Likely Electrical Load .512.1.2. ( i )

The( Tails ) between the Consumer Unit & the (Meter ) → or DNO / Isolating Switch . ( Note– An Isolator is often Not Installed bythe Distributor ) O.S.G. p/15
Adequately( Sized ) & Protected against Mechanical Damage .
523.1. )
522.6.1) AG
522.8.1.) AJ .
433.1.1.)

 

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FirstAmendment - Deleted by BS-7671:2008 . Conduit/ 514.2.1. :50:

Orange as a means of identification of an electrical conduit has beendeleted

 

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( If ) / FaultCurrent ( A ) Example : V / Z – 230V ÷ 0.32Ω = 718.75A . :gettree:

 

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Wire Résistance :

What affects the Résistance of a Wire . :15:
Answer : ConductiveElectrons moving through thewire bang into Electrons attached to Atoms . “ Facts “ This converts some ofthe Electrical Energy to Heat .

The effects the Résistance in Wires :

Length :
Cross-sectional area :
Material : ! Copper .
Temperature : °C

 

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Electrical Connections - Regulations. 526.1

Conductor terminationsare properly secure ( Tight ) withintheir terminals :speechless: